Mercury-dropping Electrodes. 389 



15. The " law " ascribed to Faraday, in § 5, would not, I 

 think, have been recognized by that philosopher. 



The mere combination of free oxygen with the metal would 

 not, according to Faraday's view, be an electrolytic action at 

 all, as might be shown by many quotations from his work, 

 e. g. " But in considering this oxidation or other direct action 

 upon the metal itself as the cause and source of the electric 

 current, it is of the utmost importance to observe that the 

 oxygen or other body must be in a peculiar condition, namely 

 in the state of combination ; and not only so but limited still 

 further to such a state of combination and in such proportions 

 as will constitute an electrolyte" *. 



An anion, according to Faraday f, is the substance which 

 '' goes to the anode of the decomposing body," and the anode 

 is the " negative extremity of the decomposing body ; " and he 

 expressly repudiates the application of the terms electro- 

 negative or electropositive to substances according as they are 

 urged by the supposed influence of a direct attraction to the 

 positive or negative pole. 



The supposition that individual atoms or molecules can 

 possess any specific electric charges of their own appears to me 

 to be of a very speculative character, but if oxygen have any 

 such charge it must surely be a negative one, since it travels 

 towards the positive pole of a voltameter. 



16. Referrinof now to S 6, the charo-ino; of the surfoces 

 does take place, according to the view 1 advocate, in an in- 

 sensibly short time, and is due to a component of the electro- 

 lyte present in large quantities ; but, as shown in § 10, it is not 

 immediately connected Avith the attainment of a maximum 

 difference of potential at a certain speed of dropping ; this effect 

 being due not to a o-radual charo-ino- but to a gradual tarnish- 

 mg — a phenomenon experimentally demonstrable, and which 

 is not improbably also the cause of the action in Lippmann^s 

 electrometer, referred to in § 7. 



In § 7 are given the phenomena on which depend the con- 

 clusion expressed in § 8. 



I have translated § 8 in full as it contains the hypothesis on 

 which so much work has been carried out, but it is evident that 

 it has only the validity of the previous sections on which it is 

 based. Indeed Ostwald, who gives a long description of his 

 arduous work with these drop[)ing electrodes, admits % that 

 the question is not whether they assume exactly the same 

 potential as the liquid, but how much the difference is ; a 



* Exp. Res. i. p. 278. 8ee also p 252. 



t Exp, lle.s. i. pp. 197-8. 



X Zeitschrift fiir physikalischc C'hemie,]. p. 588. 



